Continuity mistake: When Norma and Helen are in the salon, and they are talking about Carrie going to the prom with Tommy, Norma is getting a fancy hairdo done for the prom. But in the next gym scene, she has her plain braids and a cap on. (00:48:20)
Continuity mistake: Near the end of the film, between the time Carrie finishes her bath after the prom and the time her mother stabs her, the wetness of Carrie's hair changes from shot to shot. When she first puts on her nightgown, her hair is almost dry; later on, about when her mother says, "We'll pray," her hair is very damp; when her mother stabs her, her hair is almost dry again.
Continuity mistake: In the scene when Billy and Chris are driving for the first time in his car just before Freddy pulls up, you can see him drive past 3 times (it is easier to see him by the red cap).